Topic: Alignment Stationing Direction (C3D)

[surveyor_randy]

Okay, here is one that is puzzling us.  We have a subdivision that we are working on that has a roadway that resembles a "P"

Assume you are starting your stationing at the bottom of the "P", when C3D hits the first intersection, it turns right and stations on around that way.  We would like to have the stationing travel all the way up the back of the "P" and then around.  We couldn't figure out how to do this.  In Terramodel, it was quite easy to do.  I ended up having to recreate the centerline geometry for this portion and leave a gap.  I applied the stationing, then went in and extended the line to meet the back of the "P".  Is there an easier way to do this?  Thanks everyone!

[dfarris75]

I was able to create an alignment in a P shape and it stationed just fine. How did you go about creating it the first time?

[surveyor_randy]

I created it as a polyline.  Maybe I closed it and that is what caused the issue.  I just copied the corrected alignment, exploded it, pedit (multi)ed the segments and joined them up and tried create alignment from polyline and it stationed it correctly.  I asked our draftsman how he created the "P" portion of the centerline.  He used PEDIT and then Joined portions of it together.  Interestingly enough, when I create it the same way, it stations incorrectly.  I think that the cause may be the order of the vertex points along the polyline.  When he created this portion of the centerline, the spine of the P was not continuous and there was a segment leading up to the intersection and one leading away so the order of the vertex points was to blame.  Thanks for the reply!  At least now I've discovered a way to manually control which direction the stationing will go when it hits a point where it will intersect itself.

[dfarris75]

If you ever do run into an issue with an alignment intersecting itself and not stationing correctly you can simply create two separate alignments out of it and station them as such that the stations are continuous to give the appearance that they are one alignment.

[dgreble]

I try to avoid creating alignments from polylines and create from layout, this is probably caused by C3D06 hangover.

[sinc]

Alignments created from polylines can't be edited in the same way.  Basically, all segments in the alignment get created as entities, so you don't have options like dragging PIs and watching floating curves follow the tangents, etc.